This area chart visualizes solar radiation levels across the eight planets, ordered from Mercury to Neptune by their distance from the Sun. A smooth monotone curve connects the data points, with the area beneath filled using a vertical linear gradient that fades from semi-transparent blue to nearly transparent. The visualization uses D3 v7 APIs including `d3.scalePoint`, `d3.scaleLinear`, `d3.axisLeft`, `d3.axisBottom`, `d3.curveMonotoneX`, and `d3.area`. Data is loaded from a remote CSV file containing planetary climate measurements, with hover tooltips displaying each planet’s exact radiation value in W/m².